Method of decontamination of process chamber after in-situ chamber clean

ABSTRACT

A method and apparatus for removing deposition products from internal surfaces of a processing chamber, and for preventing or slowing growth of such deposition products. A halogen containing gas is provided to the chamber to etch away deposition products. A halogen scavenging gas is provided to the chamber to remove any residual halogen. The halogen scavenging gas is generally activated by exposure to electromagnetic energy, either inside the processing chamber by thermal energy, or in a remote chamber by electric field, UV, or microwave. A deposition precursor may be added to the halogen scavenging gas to form a deposition resistant film on the internal surfaces of the chamber. Additionally, or alternately, a deposition resistant film may be formed by sputtering a deposition resistant metal onto internal components of the processing chamber in a PVD process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent Application61/237,505, filed Aug. 27, 2009, which is incorporated by referenceherein.

FIELD

Embodiments described herein generally relate to manufacture of devicessuch as light emitting diodes, and to processes for forming group IIINmaterials for such devices. More specifically, embodiments describedherein relate to methods and apparatus for preventing contamination fromparticles or chemical residue dislodged from internal surfaces of adeposition chamber.

BACKGROUND

Group III-V films are finding greater importance in the development andfabrication of a variety of semiconductor devices, such as shortwavelength light emitting diodes (LEDs), laser diodes (LDs), andelectronic devices including high power, high frequency, hightemperature transistors and integrated circuits. For example, shortwavelength (e.g., blue/green to ultraviolet) LEDs are fabricated usingthe Group III-nitride semiconducting material gallium nitride (GaN). Ithas been observed that short wavelength LEDs fabricated using GaN canprovide significantly greater efficiencies and longer operatinglifetimes than short wavelength LEDs fabricated using non-nitridesemiconducting materials, such as Group II-VI materials.

One method that has been used for depositing Group III-nitrides, such asGaN, is metal organic chemical vapor deposition (MOCVD). This chemicalvapor deposition method is generally performed in a reactor having atemperature controlled environment to assure the stability of a firstprecursor gas which contains at least one element from Group III, suchas gallium (Ga). A second precursor gas, such as ammonia (NH₃), providesthe nitrogen needed to form a Group III-nitride. The two precursor gasesare injected into a processing zone within the reactor where they mixand move towards a heated substrate in the processing zone. A carriergas may be used to assist in the transport of the precursor gasestowards the substrate. The precursors react at the surface of the heatedsubstrate to form a Group III-nitride layer, such as GaN, on thesubstrate surface. The quality of the film depends in part upondeposition uniformity which, in turn, depends upon uniform mixing of theprecursors across the substrate.

To accomplish deposition of the layer on substrates, multiple substratesmay be arranged on a substrate carrier and each substrate may have adiameter ranging from 50 mm to 100 mm or larger. The uniform mixing ofprecursors over larger substrates and/or more substrates and largerdeposition areas is desirable in order to increase yield and throughput.These factors are important since they directly affect the cost toproduce an electronic device and, thus, a device manufacturer'scompetitiveness in the market place.

The different gases, which when combined react to form the depositionlayer, are generally provided through different pathways in a gasdistributor to the reaction chamber. As the gases exit the gasdistributor, they mix and begin reacting. Generally, the gas distributoris kept at a temperature well below the substrate temperature to avoiddecomposition of gases in the precursor pathways before the precursorgases reach the substrate. Although most reaction products are formednear the heated substrate, some begin forming as the precursors mix nearthe exit of the gas distributor, and condense and deposit on the gasdistributor. The deposits build up over many deposition cycles, untilthere is an unacceptable risk that particles formed from this unwanteddeposition will dislodge during deposition and contaminate substratesbeing processed in the chamber. Thus, there is a need for methods andapparatus to prevent or retard buildup of such deposits.

SUMMARY

Embodiments disclosed herein provide a method of cleaning group IIInitride deposits formed on a gas distributor during a processing run ina deposition chamber, the method comprising forming a sacrificialcoating on the gas distributor prior to the processing run, after theprocessing run, exposing the group III nitride deposits and thesacrificial coating to an activated halogen containing gas, and etchingthe sacrificial coating and the group III nitride deposits, wherein thesacrificial coating is etched faster than the group III nitridedeposits.

Other embodiments provide a method of removing group III nitridedeposits from a gas distributor in a process chamber, comprisingexposing the gas distributor to a halogen containing gas, reacting thehalogen containing gas with the group III nitride deposits to formvolatile species, and exposing the gas distributor to an active nitrogencontaining gas.

Other embodiments provide a method of operating a deposition chamberhaving a gas distributor with a surface exposed to the processingenvironment, the method comprising forming a sacrificial coating on thesurface of the gas distributor, depositing a group III nitride materialon a substrate in the deposition chamber and on the coated surface ofthe gas distributor by providing a group III metal precursor and anitrogen containing precursor to the deposition chamber, purging thegroup III metal precursor from the deposition chamber using the nitrogencontaining precursor, providing a halogen containing gas to thedeposition chamber, activating the halogen containing gas by heating thehalogen containing gas to a temperature above about 600° C., reactingthe active halogen containing gas with the sacrificial layer and withthe group III nitride deposits on the sacrificial coating at a pressurebetween about 100 Torr and about 200 Torr to remove the sacrificialcoating and convert the group III nitride deposits to group III halidedeposits, removing the group III halide deposits by increasing thetemperature to at least about 1,000° C. and reducing the pressure toless than about 50 Torr, and heat-soaking the gas distributor at atemperature above about 1,000° C. under an inert atmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a flow diagram summarizing a method for cleaning a chamberaccording to one embodiment.

FIG. 2 is a flow diagram summarizing a method for forming a depositionresistant layer on internal surfaces of a chamber according to anotherembodiment.

FIG. 3 is a flow diagram summarizing a method for removing unwanteddeposits from, and providing a deposition resistant layer for, internalsurfaces of a chamber according to another method.

FIG. 4 is a schematic cross-sectional view of a gas distributor usefulfor practicing embodiments of the invention.

FIG. 5A is a cross-sectional view of a gas distributor according to oneembodiment.

FIGS. 5B and 5C are close-up views of portions of the gas distributor ofFIG. 5A.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Embodiments disclosed herein generally provide methods and apparatus forpreventing buildup of deposits on components of a deposition chamber.Some embodiments provide methods for cleaning the chamber componentsperiodically, and other embodiments provide methods for reducing orpreventing deposits. In some embodiments, a coating is applied in situto a gas distributor to reduce formation of deposits on the gasdistributor around gas flow portals. In other embodiments, the gasdistributor is cleaned using active reagents, such as radicals. Suchcleaning processes may follow a halogen cleaning process, and mayprecede a coating process.

During an MOCVD or HVPE deposition process, for example, group IIImaterials may deposit on the gas distributor due to low vapor pressureof the reaction products produced in the chamber. This buildup ofdeposition products on the gas distributor and/or other chambercomponents, such as the chamber walls, may result in unwanted particlesflaking therefrom and depositing on a substrate disposed in the chamber.Some embodiments described below provide an apparatus for forming ametal nitride layer on a substrate, comprising a chamber enclosing asubstrate support and, facing the substrate support, a gas distributorhaving a deposition resistant coating. The deposition resistant coatingwill generally reduce deposition on the gas distributor, reducing thefrequency of cleaning needed. The coating may be a galliumdeposition-resistant coating, such as tungsten, chromium, molybdenum, oranother coating resistant to deposition thereon, such as siliconcarbide, silicon nitride, gallium nitride, or aluminum nitride. In someembodiment, it is also useful to use a deposition resistant coating incombination with one or more chamber component cooling devices tofurther inhibit the deposition of the group III materials on the exposedsurfaces. In one example, the one or more chamber component coolingdevices include the thermal control channel 422 and heat exchangingsystem 424 used to control the temperature of the gas distributor 400,which are further described below.

In one embodiment, a gas distributor resistant to deposition in aprocess chamber may be formed by depositing a metal coating, such astungsten, chromium, or molybdenum on an outer surface of a gasdistributor using a physical vapor deposition process, or by depositinga metal or ceramic coating, such as tungsten, chromium, molybdenum,silicon carbide, silicon nitride, gallium nitride, or aluminum nitrideon the outer surface of the gas distributor using a chemical vapordeposition process. In some embodiments, a coating may be formed in-situby providing CVD precursors such as TMG, TMA, silane, TMS, ammonia,and/or methane to a chamber having a gas distributor to be coated. Insome embodiments, the coating forms a seasoning layer on the gasdistributor. Exemplary CVD coatings formed from such precursors includegallium nitride, aluminum nitride, silicon nitride, and silicon carbide.

Deposits that build up during deposition may be removed by one or morecleaning processes. In one embodiment, a halogen containing gas isprovided to the chamber through the gas distributor having deposits tobe removed. The halogen gas reacts with the deposits, which generallycontain metal-rich group III/V deposition products such as gallium (Ga),indium (In), aluminum (Al), gallium nitride (GaN), indium nitride (InN),aluminum nitride (AlN), and combinations thereof, producing halid solidsand nitrogen containing gases which are removed from the chamber, thehalide solids being removed from the chamber by volatilizing at hightemperature. In another embodiment, halide residues that may be left bya halogen cleaning process are removed by providing active species tothe chamber. In some cases the active species are formed by applyingelectrical energy (e.g., generating RF plasma), optical energy, orthermal energy to the gas or vapor species. The active species scavengeany remaining deposits, including halide residues. In some embodiments,the two cleaning processes are combined in a two-stage cleaning process,while in others the two cleaning steps may be performed at differenttimes. Additionally, cleaning processes may be combined with coatingprocesses in some embodiments.

Cleaning Methods

FIG. 1 is a flow diagram summarizing a cleaning method 100 according toone embodiment. At 102, a cleaning gas, such as a halogen containinggas, is provided to a chamber having a coating of deposition products,such as metal-rich group III nitrides or other group III/V reactionproducts, such as group III metals, on internal components thereof, suchas on the gas distributor. Some exemplary group III deposition productsthat may be removed by the cleaning method 100 include Ga, In, Al, GaN,InN, AlN, aluminum gallium nitride (AlGaN), indium gallium nitride(InGaN) and the like. The coating may be continuous or discontinuous,and may be merely deposits from the deposition process formed on gasflow portals of a gas distributor. The halogen containing gas may be anelemental halogen gas, such as chlorine, fluorine, bromine, or iodinegas, or a hydrogen halide gas, or any mixture thereof. In some examples,the cleaning gas comprises a chlorine (Cl₂) gas, a fluorine (F₂) gas, ahydrogen iodide (HI) gas, an iodine chloride (ICl) gas, an HCl gas, anHBr gas, a HF gas, a BCl₃ gas, a CH₃Cl gas, a CCl₄ gas and/or an NF₃gas.

In one embodiment, to clean a gas distributor having deposits thereon asdescribed above, chlorine gas (Cl₂) is provided to a chamber containingthe gas distributor, optionally with a non-reactive carrier gas, such asargon, helium, or nitrogen gas. The chlorine gas is heated to atemperature of at least about 600° C., such as between about 650° C. andabout 750° C., by heating an internal surface of the chamber, such as asubstrate support disposed in the chamber facing the gas distributor.The resulting gas mixture may be about 5-100% chlorine gas in carriergas, by total gas volume, such as between about 50% and about 80%chlorine gas in carrier gas. The chamber pressure is maintained betweenabout 100 Torr and about 200 Torr during exposure of the gas distributorsurfaces to the chlorine gas. The chlorine gas converts the group IIInitrides on the gas distributor surfaces to group III halide solids.

At 104, the coating of deposition products is etched away from theinterior of the chamber. The halogen containing gas reacts with thedeposits to form volatile metal halides, which are removed from thechamber. In embodiments featuring chlorine gas, the chlorine reacts withthe metal-rich deposits to form gallium chloride (GaCl₃), indiumchloride (InCl₃), and aluminum chloride (AlCl₃), which are volatile atlow pressures. In the embodiment featuring chlorine gas as the reactant,the chlorine gas may be provided at a flow rate between about 1 slm andabout 20 slm, with carrier gas flow rate between about 0 slm and about20 slm, at pressures between about 0.01 Torr and 1,000 Torr, such asbetween about 100 Torr and about 200 Torr, and temperatures betweenabout 20° C. and about 1,200° C., such as above 600° C., for examplebetween about 650° C. and about 750° C.

The halogen gas converts the group III nitride deposits to group IIIhalide solids. Following conversion of the group III nitrides to groupIII halide solids, the group III halide solids are removed byvaporization or sublimation. The chamber temperature is increased to atleast about 1,000° C., such as between about 1,050° C. and about 1,200°C., for example about 1,100° C. The chamber pressure is lowered to about50 Torr or below. The halogen gas flow may be maintained during a firstphase of the removal operation, and then the halogen gas flow may bediscontinued and the carrier gas flow continued during a second phase ofthe removal operation. During such a second phase, the chambertemperature may be further increased to at least about 1,100° C. In theembodiment described above, conversion of the group III nitride depositsto group III halide salts takes about 5-60 minutes, depending on thethickness of the coating, and removal of the group III halide solidstakes at least about 10 minutes, such as between about 10 minutes andabout 20 minutes, to complete.

In some embodiments, the conversion and removal may be accomplished incycles. In one embodiment, conversion may proceed for about 1 minute andremoval for between about 10 seconds and about 20 seconds in one cycle.The cycle is then repeated until the group III nitride deposits areremoved, which may take between 50 and 100 cycles. In anotherembodiment, conversion may proceed for about 5 minutes and removal forabout 1 minute, the cycle being repeated about 10 times. In each cycle,the temperature and pressure of the chamber are moved between theconversion and removal conditions described above. Cycle repetitions andconversion and removal times per cycle depend on the thickness of thegroup III nitride deposits on the chamber surfaces. Thicker depositstake more time and repetitions to remove.

The halogen treatment may leave halogen containing residues on chambersurfaces, so a second optional cleaning process may be performed at 106and 108. At 106, a nitrogen containing gas is provided to the chamber,and at 107 the nitrogen containing gas is activated. At 108, the activenitrogen containing gas is allowed to react with residual halogenspecies in the chamber to purge the halogen species from the chamber. Insome embodiments, the nitrogen containing gas, which may be ammonia(NH₃), nitrogen gas (N₂), hydrazine (H₂N₂) or other simple nitrogencontaining compound, may be activated into ions or radicals. In oneembodiment, ammonia is heated to a temperature of at least about 500° C.by heating the substrate support. The heating activates the nitrogencontaining gas, causing compounds in the gas to dissociate, pyrolyze,ionize, or form radicals. In other embodiments, the nitrogen containinggas may be heated remotely and provided to the gas distributor as a hotgas. The gas distributor is generally cooled during deposition processesto avoid unwanted reactions inside and near the distributor. During somecleaning processes, cooling of the gas distributor may be discontinuedto facilitate thermal activation of cleaning compounds. Heating of thesubstrate support may be accomplished by any convenient means, such asby disposing heat lamps proximate the substrate support. In oneembodiment, heat lamps are arrayed below the substrate support. Otherembodiments may feature a substrate support heated by internal means,such as resistive or hot fluid heating.

The nitrogen containing gas may be provided with a carrier gas. In oneexample ammonia is provided along with nitrogen gas as a carrier. Thegas mixture may be between about 10% ammonia and about 80% ammonia byvolume in nitrogen gas.

The activation of operation 107 may proceed by different methods. In oneembodiment, the gas distributor is exposed to hot ammonia gas, heated toat least about 1,000° C., to form highly reactive radical species thatscavenge the remaining halogen from the chamber. The heating may beaccomplished by heating the substrate support or the gas distributor, orby heating the ammonia remotely and providing the heated gas to thechamber. In another embodiment, a nitrogen containing gas is activatedin a remote chamber by applying electromagnetic energy, such as electricfields or thermal, UV, or microwave radiation. The activated nitrogengas, containing radical species, is then provided to the chamber toremove halogen residues. The activated nitrogen species convert theremaining halogen residues back to metal nitride to prevent halogenspecies from being incorporated into devices subsequently formed in thechamber. The risk that the nitrides will contaminate such devices isreduced because most of the nitride deposits are removed, leaving atmost a very thin coating or residue that is very unlikely to separatefrom the gas distributor or other chamber component. In otherembodiments, the gas may be exposed to electric fields, thermal, UV, ormicrowave radiation in situ.

A nitrogen containing gas may be provided at a flow rate between about 1slm and about 50 slm, at chamber pressure of between about 0.01 Torr andabout 1,000 Torr. The nitrogen containing gas may be activated byheating to a temperature between about 500° C. and about 1,200° C., suchas between about 900° C. and about 1,100° C., by contacting the gas witha heated substrate support spaced apart from the gas distributor, or byheating outside the chamber. At such temperatures, the thermal energyactivates the nitrogen containing gas. If UV, microwave, or electricalenergy is used to activate the nitrogen containing gas, the chambertemperature may be between about 20° C. and about 600° C., such asbetween about 100° C. and about 300° C.

Prior to the halogen gas exposure of FIG. 1, the chamber may be purgedto remove gases or substances that may be incompatible with the halogengas. Metal precursor species such as TMG, TMA, and TMI, in particular,are removed prior to feeding halogen gas to avoid unwanted reactionsthat may consume the halogen gas and generate further deposits. Thechamber may be purged using an inert gas such as nitrogen gas or argon,or the chamber may be purged using a non-metal reagent such as ammonia.In a deposition process wherein a metal nitride is formed from a metalprecursor and ammonia, flow of the metal precursor may be discontinuedand the chamber purged using the ammonia gas. Alternately, the ammoniagas may be replaced with an inert gas such as nitrogen, argon, orhydrogen to purge the chamber. During the chamber purge, the chamberpressure may be cycled to enhance removal of fugitive species adheringthe chamber surfaces. A throttle valve between the chamber and thevacuum pump may be opened and closed repeatedly to cycle the chamberpressure up and down a desired number of times, for example 3-5 times.

Prior to the halogen gas exposure of FIG. 1, the chamber may besubjected to a baking operation to remove metal nitride deposits fromchamber surfaces such as the substrate support and chamber liner, ifany. Chamber temperature is increased to at least about 1,050° C. for aduration of 5-10 minutes or more. Hydrogen gas may be provided toenhance removal of deposits. The baking operation also enhances removalof deposits from the gas distributor.

Following the halogen gas clean and residual halogen removal operationsof FIG. 1, the chamber may be subjected to a baking operation to enhanceremoval of halogen species from chamber surfaces. Chamber temperature isset to at least about 1,050° C. If a mixture of ammonia and nitrogen gasis used for residual halogen removal, the flow of ammonia may bediscontinued, and the flow of nitrogen maintained during the post-cleanbaking operation. To aid removal of fugitive halogen species, thechamber pressure may be cycled between about 200 Torr and about 1 Torrby opening and closing the vacuum throttle valve. The post-clean bakingoperation may proceed for a duration of about 5-10 minutes or more. Inone embodiment, flow of nitrogen gas may be replaced during the bakingoperation by a flow of hydrogen gas to help scavenge residual halogenspecies.

Coating Methods

FIG. 2 is a flow diagram summarizing a method 200, according to anotherembodiment, for forming a layer resistant to deposition of gallium orgallium compounds on internal surfaces of a chamber. A method such asthe method 200 is useful for treating chamber components to prevent orslow deposition of gallium-rich compounds on the components of aprocessing chamber. In this method, one or more precursor gases areprovided to a processing chamber at 202. The gases are generallyselected to facilitate deposition of a layer on the internal componentsof the chamber. The gases may be provided through different pathways, ifdesired, to prevent reaction before the gases arrive in the chamber. Forexample, if two gases are used, a first gas may be provided to thechamber through a first pathway, and a second gas through a secondpathway. A gas distributor having multiple pathways is further describedin connection with FIGS. 5A and 5B.

It should be noted that the method 200 may be performed in the chamberhaving the internal surfaces to be coated, or components of the chambermay be placed in another processing chamber to be coated. For example,if a PVD process is performed, the chamber components may be disposed ina PVD chamber, and the process gas provided to the chamber may be a PVDprocess gas, such as argon or helium.

At 204, a layer is deposited on internal surfaces of the chamber. In oneembodiment, two or more gases react to deposit a layer by a CVD process,which may be performed in the chamber having the internal surfaces to becoated, or in a separate chamber having components to be coated disposedtherein. In one embodiment, the layer is deposited by a PVD process inwhich a material resistant to gallium or gallium compounds, or othergroup III compounds, is sputtered onto chamber components. In anotherembodiment, a layer is deposited by providing activated species to thechamber having the surfaces to be coated, and reacting the activatedspecies to form the layer.

The layer may have a thickness between about 10 Å, about two unit celldimensions of a crystal lattice, and about 1 mm. A layer or coatinghaving a thickness of at least about two unit cell layers, such as about10 Å, will retard growth of deposits on a gas distributor in most cases.The coating may be any thickness up to about 1 mm, but will generally beapplied in a way to avoid occluding openings in the gas distributor fordispensing process gases. In one embodiment, a metal, such as tungsten,chromium, molybdenum, or a combination or alloy thereof, or anotherrefractory metal, is sputtered onto a gas distributor to a thickness ofbetween about 10 Å and about 1 mm, such as between about 10 Å and about10 μm, for example between about 10 Å and about 1,000 nm. In anotherembodiment, TMG and ammonia are provided to a chamber containing the gasdistributor to be coated thereby, depositing gallium nitride on the gasdistributor. In another embodiment, TMA and ammonia are provided to thechamber to deposit aluminum nitride on the gas distributor. In anotherembodiment, silane and methane are provided to the chamber to depositsilicon carbide on the gas distributor. In another embodiment, silaneand/or TMS and ammonia are provided to deposit silicon nitride on thegas distributor. Coatings formed by CVD processes may have thicknessbetween about 100 nm and about 200 nm because gas flowing through theopenings in the gas distributor reduces film formation in and around theopenings.

In other embodiments, a refractory metal such as tungsten, chromium,molybdenum, titanium, zirconium, hafnium, vanadium, niobium, tantalum,ruthenium, osmium, rhodium, yttrium, and iridium, or ceramics (oxides)thereof, other derivatives thereof, combinations thereof, or alloysthereof, may be sputter coated or plated onto a stainless steel gasdistributor according to processes such as CVD, PVD, plasma spraying,electroplating, and/or electroless plating that are known in the art.Various aluminum containing materials may also be applied by CVD or PVD,including aluminum itself, alumina, aluminum nitride, and alloys ofaluminum with other metals listed above, silicon, or carbon. Otherdielectric materials that may be used for coatings include boron nitrideand silicon carbide. Any material that forms a tight metallurgical bondwith stainless steel, such as aluminized steel, is suitable for coatinga stainless steel gas distributor of an MOCVD chamber to retard orprevent buildup of deposition products.

Formation of the coating may be aided by activation of one or morechemical precursors. A precursor is generally activated byelectromagnetic means, such as by exposure to an electric field, forexample an RF field, to ionize a portion of the precursor, by exposureto thermal energy to dissociate, crack, or ionize the precursor, or byexposure to radiation, such as UV or microwave radiation. In someembodiments, one or more precursors may be irradiated by UV or microwaveradiation, or exposed to an RF field, in an activation chamber, and theactive precursors provided to the chamber containing the gas distributorto be coated. In one embodiment, the substrate support is heated to atemperature of about 600° C. to about 1,000° C. to activate one or moreprecursors and cause a reaction to deposit a coating on the gasdistributor. In one embodiment, a first precursor is provided to thechamber at a flowrate between about 10 sccm and about 1,000 sccm, suchas about 50 sccm, and a second precursor is provided at a flowratebetween about 10 slm and about 300 slm, such as about 50 slm. A carriergas, such as nitrogen gas, argon, or helium, may be provided with eitherthe first or second precursors. As described above, the first precursormay be silane, TMS, TMG, or TMA, or another electrophillic metal ormetalloid compound, or a mixture thereof. The second precursor isgenerally ammonia or methane, or another nucleophile.

In one embodiment, a deposition precursor and a radical precursor areprovided to a processing chamber to deposit a coating on a gasdistributor for an MOCVD or HVPE reactor. The deposition precursor maycontain a group 13 transition metal or a metalloid, and the radicalprecursor may contain radicals comprising nitrogen, hydrogen, carbon, orany mixture thereof. The radicals may be generated in the processingchamber by exposing the radical precursor to electromagnetic energy suchas an electric field, for example a capacitive RF field, a magneticfield, for example an inductive RF field, or electromagnetic radiation.The electromagnetic radiation may be thermal, which may be delivered byheating the gas distributor, or UV or microwave delivered by an emitter.In other embodiments, exposure to the electromagnetic energy may beperformed in a separate activation chamber, and the radical precursorcontaining radicals may then be provided to the processing chambercontaining the gas distributor to be coated. In embodiments wherein theradical precursor is activated in a separate processing chamber,deposition of a coating on the gas distributor is performed attemperatures of at least about 200° C.

The deposited layer may optionally be heat treated at 206. During theheat treatment, flow of reactive gases is generally discontinued, andcomponents having the newly deposited layer are heated to a temperatureof at least about 500° C. to cure or harden the deposited layer. Heatingto high temperatures may also result in smoothing of some depositedlayers, such as metals. High temperature treatment may also aid indriving away fugitive reactive species that may remain in the depositedlayer.

Precursor gases may be purged from the chamber at 208 to prepare forsubsequent processing. In an embodiment wherein a deposition resistantlayer is deposited in situ, the precursor gases are purged from thechamber to draw fugitive reactive species out of the deposited layer,and to purge any reactive species adsorbed onto any surface of thechamber interior.

Cleaning and Seasoning

FIG. 3 is a flow diagram illustrating a method 300 according to anotherembodiment. At 302, a cleaning gas, such as a halogen gas is provided tothe chamber to etch away surface contaminants. The contaminants aregenerally the undesirable deposition products described earlier. In oneexample, the halogen gas may be an elemental halogen, such as chlorinegas (Cl₂) or fluorine gas (F₂), or a hydrogen halide gas, such as HCl orHF. The halogen species react with the surface contaminants, which aregenerally metal or metal nitride, to produce volatile metal halides. Thechamber is maintained under vacuum to minimize halogen residues onchamber surfaces. Because some metal halides decompose at relatively lowtemperatures, chamber temperature may be maintained below about 200° C.,such as between about 20° C. and about 200° C., for example about 100°C. Exposure to the halide species continues for between about 5 min andabout 10 min.

At 304, the halogen gas is purged from the chamber using an inert gassuch as argon (Ar), helium (He), or nitrogen (N₂). A plasma is formedfrom the inert gas at 306. The inert gas is provided to a plasma chamberand energized using any appropriate form of electromagnetic energy, suchas electric fields (DC or RF) or electromagnetic radiation such asthermal, UV, or microwave radiation.

The inert gas plasma is provided to the process chamber at 308. Theprocess chamber may have residual halogen species from the halogencleaning stage 302. The inert gas plasma comprises reactive species,such as ions and radicals, that react with, soften, and etch away thecontaminants. In some embodiments, a plasma pre-treatment may increasethe effectiveness of a subsequent seasoning process. In one embodiment,argon, helium, or nitrogen, or any combination thereof, is activated ina plasma chamber by flowing a gas mixture comprising one or more ofthose components at a flow rate of about 1 slm to about 40 slm throughthe plasma chamber and applying electromagnetic energy to the gas in thechamber. The electromagnetic energy may take the form of an RF or DCelectric field applying between about 200 Watts and about 5,000 Watts ofpower to the gas, or it may take the form of thermal, UV, or microwaveenergy at similar power levels.

At 310, the inert gas plasma is purged from the chamber using a gas thatscavenges any residual halogen from chamber surfaces. Residual halogenis purged from the chamber and scavenged from chamber surfaces to avoidincorporation of halogen species in subsequent deposition processes.Examples of gases that may scavenge residual halogen from chambersurfaces are nitrogen containing gases, such as ammonia (NH₃), nitrogengas (N₂), or hydrazine (H₂N₂), and hydrogen containing gases, such assimple hydrocarbons methane (CH₄), ethane (C₂H₆), ethylene (C₂H₄), andacetylene (C₂H₂), or other hydrides, such as silane (SiH₄) or germane(GeH₄).

The scavenging gas may be activated to increase reactivity. Radicals ofnitrogen or hydrogen may be formed from compounds such as these byactivating them using electromagnetic energy such as electric fields,for example an RF field, or electromagnetic radiation, such as thermal,UV, or microwave radiation. Thermal energy may be provided bymaintaining the chamber at a temperature of about 600° C. or higher,such as between about 900° C. and about 1,100° C., for example about1,000° C. UV or microwave radiation may be coupled into the gas in anactivation chamber remote from the chamber being cleaned. Purging withthe scavenging gas is generally maintained for between about 5 min andabout 10 min. Prior to introducing the scavenging gas, plasma generationusing the inert gas may be discontinued, and flow of the inert gascontinued for a duration of between about 10 seconds and about 30seconds to purge most of the active species and cleaning byproducts fromthe chamber.

A deposition resistant film may be applied to chamber components at 312or 314. At 312, a metal or silicon containing gas such as TMG, TMA, TMI,or TMS may be added to the scavenging gas from 310 to deposit a film oninternal surfaces of the chamber. A film such as silicon carbide (SiC),silicon nitride (SiN), gallium nitride (GaN), aluminum nitride (AlN),which may be p-doped or n-doped by including dopants such as boron,derived from borane or diborane, or phosphorus, derived from phosphine,or films composed of more than one such component, may be more resistantto deposition in an MOCVD or HVPE process than the clean chambersurfaces themselves. Formation of the deposition resistant film may beenhanced by maintaining activation of the scavenging gas, so thatradical species from the activated scavenging gas react with the metalor silicon containing gas. Maintaining the chamber temperature highenough to activate the scavenging gas, but low enough to encouragedeposition of the reaction products on the chamber surfaces, such asbetween about 600° C. and about 800° C., also enhances formation of thedeposition resistant film. Chamber temperature may be maintained byheating the substrate support, in some embodiments.

Alternately, at 314, a deposition resistant film may be deposited usinga PVD process. Chamber components to be coated with the resistant filmare disposed in a PVD chamber, and a coating is sputtered onto thecomponents. Materials such as those described above may be sputtercoated onto the chamber components. Alternately, resistant metals, suchas tungsten, chromium, molybdenum, or combinations or alloys thereof,may be sputter coated.

A heat treatment operation may be advantageously performed at any stageof the processes of FIGS. 2 and 3. A heat treatment process may comprisesetting an internal temperature of the chamber between about 800° C. andabout 1,200° C. at a pressure between about 5 Torr and about 300 Torrfor a duration of about 30 seconds to 10 minutes, such as a duration ofabout 60 seconds to 5 minutes. The heat treatment may have differenteffects when performed at different stages, but is generally used todensify and/or harden coatings and seasoning layers and to volatilizesurface-adhered species.

In some embodiments, prior to performing a deposition process, it may bebeneficial to pre-coat chamber internal surfaces, including the gasdistributor, with a stabilizing layer without performing a cleaningoperation. Coating with a stabilizing layer may be faster than a fullcleaning operation, and may allow processing to continue withoutperforming the entire cleaning operation. A stabilizing layer may havesimilar composition to layers that may be deposited on a substrate inthe chamber to minimize the possibility of contaminating such substrateswith foreign material. A stabilizing layer may be formed by flowing ametal organic precursor such as TMS, TMA, TMG, and/or TMI and a reducingreagent, such as NH₃ and/or H₂ into the chamber and activating the gasmixture, according to process conditions described above. A siliconcarbide stabilizing layer may also be formed from a mixture of silaneand methane. A stabilizing layer having a thickness between about 0.2 μmand about 2.0 μm will stabilize any deposits that may remain on chambersurfaces from prior processes.

The processes of cleaning, coating, seasoning, baking, and stabilizingmay be performed in any advantageous combination with respect todeposition processes. In one embodiment, after each deposition process,cleaning, coating, seasoning, and stabilizing are performed prior to thenext deposition process. In another embodiment, baking and stabilizing,or just stabilizing, are performed after each deposition process, whilecleaning, coating, and seasoning are performed after a plurality ofdeposition processes. In another embodiment, N deposition processes areperformed between stabilizing operations, and M stabilizing cycles areperformed between cleaning and seasoning operations, with N being 1-20deposition processes, and M being 0-5 stabilization cycles. Thickness ofthe stabilization layer may be adjusted based on number of depositioncycles between stabilization operations. For example, a thickerstabilization layer may be formed after a high number of sequentialdeposition processes.

Stabilizing may be accomplished in some embodiments by soaking thechamber in an atmosphere comprising the metal organic compound to beused in a subsequent deposition process. For example, before depositinga gallium containing layer, a gas comprising TMG, optionally with aninert carrier gas such as nitrogen or hydrogen, may be provided to thechamber for a soak period of about 30 seconds to about 30 minutes, forexample about 10 minutes. Soaking is generally performed at a chamberpressure between about 10 Torr and about 300 Torr at temperaturesranging from about 20° C. to about 1,000° C. Deposition may then beginby adding a deposition precursor such as ammonia to the gas mixture inthe chamber. Similar stabilizing may be performed prior to deposition ofaluminum, silicon, and indium layers by soaking in TMA, TMS, and TMI,respectively. Prior to deposition cycles in which dicyclopentadienylmagnesium (Cp₂Mg) is used as a p-type dopant for a multi-quantum welllayer, the chamber may be advantageously soaked in Cp₂Mg to accomplishstabilization. Stabilizing with a soak process may be performed inaddition to, or instead of, forming a stabilization layer.

In some embodiments, more than one film may be applied to chambercomponents to retard formation of deposits on chamber internal surfacesduring a deposition process. For example, chamber components may besputter coated with a resistant metal such as those described above in aPVD chamber, and then CVD coated with silicon or metal compounds.Deposits formed on such films may be stripped using processes describedelsewhere herein, leaving the metal film, and perhaps portions of theCVD film, and the CVD film may be replaced following the strippingprocess, as described above. In other embodiments, a homogeneous filmcomprising two or more resistant materials, for example gallium nitride,silicon nitride, silicon carbide, or aluminum nitride doped withtungsten, chromium, molybdenum, or any combination thereof, may also beformed by adding one or more precursors comprising any of those metalsto a CVD film formation process.

Apparatus

FIG. 4 is a schematic cross-sectional view of a gas distributor 400 thatmay be used in a MOCVD or HVPE deposition chamber, and may be useful forpracticing embodiments described herein. The gas distributor 400 isshown in proximity to a chamber wall 402 and a substrate support 404. Inoperation, a substrate is generally disposed on the substrate support404, and gases are provided to a processing region 406 defined by thesubstrate support 404, the chamber wall 402, and the gas distributor400.

The gases are provided through the gas distributor 400 by a chemicaldelivery module 408 via a plurality of pathways. A first pathway 410 anda second pathway 412 are in communication with the chemical deliverymodule 408. The first pathway 410 delivers a first precursor or gasmixture to the processing region 406 via a first conduit 414 and a firstplurality of outlets 416. The second pathway 412 delivers a secondprecursor or gas mixture to the processing region 406 via a secondconduit 418 and a second plurality of outlets 420. A thermal controlchannel 422 is coupled to a heat exchanging system 424 via a thermalcontrol pathway 426. A thermal control fluid flows from the heatexchanging system 424 through the thermal control pathway 426, throughthe thermal control channel 422, and exits through an exit portal 428,from which the thermal control fluid may be returned to the heatexchanging system 424, if desired. Process gases generally exit thechamber through an exhaust channel 436 that communicates with one ormore exhaust ports 438, which communicate with a vacuum system (notshown).

In some embodiments, a central pathway 432 is provided through the gasdistributor 400 for use with a remote plasma source 430. The remoteplasma source 430 receives precursors from the chemical delivery module408, activates them by forming a plasma in the remote plasma source 430,and provides the activated species to the processing region 406 via thecentral pathway 432. The central pathway 432 may also be used, in someembodiments, to provide gases that have not been activated to theprocessing region 406. In some embodiments, a cleaning gas or precursormay be provided directly to the processing region 406 via, for example,the central pathway 432.

The gas distributor 400 of FIG. 4 has a bypass pathway 434 disposedthrough a peripheral region of the gas distributor 400 for supplyingprocess gases to the processing region 406 without using the precursorpathways 414 and 418. Such bypass pathways may be useful for cleaning,seasoning, conditioning or other processes.

FIG. 5A is a cross-sectional view of a gas distributor 500 for adeposition chamber that may benefit from one or more processes describedherein. The gas distributor 500 comprises a first plurality of openings502 and a second plurality of openings 504, each of which surrounds oneof the first plurality of openings 502, such that each opening 502 isconcentrically aligned with an opening 504. The first plurality ofopenings 502 is in communication with a first gas pathway 506 and afirst gas inlet 508, the first gas pathway comprising a plenum 518 and ablocker plate 520 having a plurality of portals 522 formed therethrough.The second plurality of openings 504 is in communication with a secondgas pathway 510 and a second gas inlet 512. The first and secondpluralities of openings 502 and 504 are formed in a surface 514 of thegas distributor 500 that faces a processing volume 516 adjacent to thesurface 514. The first and second gas pathways 506 and 510 facilitateproviding process gases to the processing volume 516 without priormixing.

A central opening 524 in the surface 514 is in communication with athird pathway 526 and a third gas inlet 528. The third pathway 526provides a means to flow process gases into a central portion of theprocessing volume 516 while bypassing the first and second plurality ofopenings 502 and 504, if desired. A side wall 530 and lid portion 534 ofthe gas distributor 500 may have one or more openings 532 formedtherethrough and in communication with a fourth gas inlet 536, or aplurality thereof, for flowing process gases into the processing volume516 while bypassing the gas distributor altogether.

FIG. 5B is a close-up view of a portion of the gas distributor 500 ofFIG. 5A. A coating 538 is provided over the surface 514 of the gasdistributor 500. The coating 538 of FIG. 5A is a CVD coating, asdescribed elsewhere herein. The coating 538 covers portions of thesurface 514 facing the processing volume 516, but does not penetrate theopenings 502, 504, and 524.

FIG. 5C is a detail view of the region around an opening 504 of the gasdistributor 500. The opening 504 has a dimension “d”, defined by thedistance between opposite walls of the opening 504. The coating has athickness “t”, which is generally between about 100 nm and about 200 nm.An exclusion zone “e” surrounding the opening 504 is not coated due toflow and mixing of gases exiting opening 504 during deposition. Byforming the coating using gas flow rates substantially similar to thoseused when depositing a layer on a substrate, the coated area of the gasdistributor substantially matches the area that receives deposits whenprocessing a substrate, so the exclusion zone “e” is sized such thatmetal nitride deposits do not form in the exclusion zone “e”. In oneembodiment, the exclusion zone “e” has a dimension that is less thanabout 50% of the opening dimension “d”. The coating 538 tapers inthickness approaching the exclusion zone “e”. The distance over whichthe coating 538 tapers is typically between about 10% and about 20% ofthe dimension “d” of the opening 504, such that the average taper angleα is between about 0° and about 5°, depending on the thickness “t”.

In one embodiment, the coating may comprise more than one depositedlayer. For example, a tungsten film may be deposited first on the gasdistributor 500, followed by a CVD film of the kind described above(i.e., silicon nitride, silicon carbide, gallium nitride, aluminumnitride). In another embodiment, a tungsten-doped CVD film may be formedon the gas distributor 500 to improve the resistance of the film todeposition products. In a CVD process to form a film of one of thecompounds listed above, a tungsten precursor may be provided to thechamber with the other precursors to add tungsten to the deposited film.In another embodiment, a tungsten-doped CVD film may be formed over atungsten film deposited by PVD or CVD processes known in the art. Ineach of these embodiments, chromium or molybdenum may be used in placeof, or in addition to, tungsten.

The coating 538 may be heat treated to improve its hardness, smoothness,or inertness to deposition. Additionally, a bilayer or multilayer filmmay be heat treated to improve adhesion of the various layers together.A heat treatment such as that described above will generally suffice toharden the film to process conditions.

In operation, a first precursor is provided to the processing volume 516through the first gas pathway 506, and a second precursor is provided tothe processing volume 516 through the second gas pathway 510. The firstprecursor may comprise a group III material such as gallium, aluminum,or indium. The group III material may be a metal organic precursor suchas trimethyl gallium (TMG), trimethyl aluminum (TMA), or trimethylindium (TMI), or other metal organic compound. The second precursor istypically a nitrogen containing precursor, such as ammonia. The firstand second precursors mix upon exiting the gas distributor, and react toform a group III nitride layer on the substrate, which is generallydisposed on a substrate support arranged facing the gas distributor, asin the substrate support 404 of FIG. 4. A carrier gas such as nitrogen,hydrogen, argon, or helium, may be provided with the first or secondprecursors, and the first and second precursors may be blends ofmultiple components. For example, the first precursor may be a mixtureof TMG, TMA, and/or TMI, and the second precursor may be a mixture ofammonia and other nitrogen compounds, such as hydrazine or a loweramine.

Sacrificial Coating

In one embodiment, the coating applied to the gas distributors of FIGS.5A-5B may be a sacrificial layer comprising silicon, aluminum, or both.A layer comprising nitrides of silicon and/or aluminum may be formed ona surface of the gas distributor facing the processing environment.During the cleaning operations described above to remove metal nitridedeposits formed on the sacrificial layer, the active halogen gas etchesthe sacrificial layer faster than the deposits are converted or removed,removing the sacrificial layer behind the deposit layer, and exposingmore surface area of the deposit layer to the halogen gas, increasingthe rate of reaction with the halogen gas. The sacrificial layer may bean aluminum nitride layer, a silicon nitride layer, or a mixturethereof. In some embodiments, the sacrificial layer may be a bilayer of,for example, silicon and silicon nitride or aluminum and aluminumnitride. In some embodiment, after performing a cleaning process (e.g.,FIG. 3, at 302), which removes the prior deposited sacrificial layer andother chamber deposits, a new sacrificial layer is deposited on thesurface of the chamber components before a device formation layer (e.g.,one or more group III layers) is deposited on one or more substrates inthe processing chamber.

The sacrificial layer may be formed in a CVD process by providing asilicon or aluminum precursor, or both, such as TMS, silane or TMA, tothe chamber to form the sacrificial layer on the chamber components. Inone embodiment, a silicon or aluminum precursor and a nitrogencontaining gas, such as any of those described above, are provided tothe processing region of the processing chamber. In one embodiment,ammonia is used as the nitrogen containing gas. A carrier gas such ashydrogen or argon may be provided with both the precursor gas mixtureand the nitrogen containing gas. Chamber temperature is generallymaintained above 1,000° C., for example between about 1,100° C. andabout 1,200° C., during formation of the sacrificial layer, and chamberpressure is maintained between about 100 Torr and about 200 Torr.

In one embodiment, a mixture of ammonia and hydrogen is flowed into thechamber at about 60 sLm. The ammonia flow rate may be between about 5sLm and about 30 sLm, for example about 25 sLm. The flow of theammonia/hydrogen mixture may be established by starting flow of thehydrogen gas and then flowing the ammonia gas into the hydrogen carriergas. Chamber temperature and pressure are established as describedabove, and flow of a precursor mixture comprising TMA and hydrogen isstarted. Flow rate of the precursor mixture is generally close to theflow rate of the ammonia/hydrogen mixture, about 60 sLm, with TMA flowbetween about 0 sLm and about 20 sLm, for example about 15 sLm. Thestreams mix and react, depositing a layer of aluminum nitride on the gasdistributor. Maintaining the reaction for a duration of between about 10minutes and about 30 minutes will deposit a layer having a thicknessbetween about 100 nm and about 200 nm on the gas distributor.

In another embodiment, the sacrificial layer may include a layer ofmetal nitride, for example gallium nitride. The flow of the silicon oraluminum precursor is generally replaced with a metal precursor as thereaction continues, and deposition of silicon or aluminum transitions todeposition of metal. In one embodiment, flow of TMA is replaced withflow of TMG at the same flow rate to deposit a thin layer of galliumnitride over a layer of aluminum nitride. In another embodiment, thesacrificial layer may comprise three layers, for example a layer ofaluminum, a layer of aluminum nitride, and a layer of gallium nitride.

At the conditions described above, the coating of gallium nitride, orother metal nitride (indium, etc.), doped or undoped, is a low qualitylayer, rich in metal and having a morphology that comprises a metalmatrix with metal nitride domains. The metal nitride domains will alsotypically have nitrogen vacancies. The structure of the layer reducesaffinity for deposition of metal nitrides on the layer.

In all the embodiments of deposition and cleaning described above, itshould be noted that operations depending on interaction of processgases with the gas distributor may be enhanced by flowing one or moreprocess gases through a gas inlet that bypasses the gas distributor. Forexample, in the embodiment of FIG. 5A, the opening 532 formed throughthe sidewall 530 of the gas distributor 500 may be beneficially used toroute a halogen gas for a cleaning operation, a purge gas for a purgeoperation, or a nitrogen containing gas for a scavenging or depositionoperation. Flowing one or more gases through a bypass pathway directsthe process gases into more intimate contact with the surface of the gasdistributor.

The foregoing description describes embodiments wherein internalsurfaces of a chamber are cleaned, and one or more films are optionallydeposited on internal surfaces of a processing chamber by feeding CVDprecursors through the gas distribution assembly of the chamber. Itshould be noted that alternate embodiments may feed precursors throughone or more portals in sidewalls of the chamber, or through one or moreportals in the bottom of the chamber, or any combination of feed throughthe gas distributor, sidewalls, and bottom of the chamber. Feedingprecursor and/or cleaning gases through the sidewalls and bottom of thechamber may enhance exposure of chamber internal surfaces to thereactive components of the precursors by altering gas flow patternsthrough the chamber.

While the foregoing is directed to embodiments of the invention, otherand further embodiments of the invention may be devised withoutdeparting from the basic scope thereof.

1. A method of cleaning group III nitride deposits formed on a gas distributor during a processing run in a deposition chamber, the method comprising: forming a sacrificial coating on the gas distributor prior to the processing run; after the processing run, exposing the group III nitride deposits and the sacrificial coating to an activated halogen containing gas; and etching the sacrificial coating and the group III nitride deposits, wherein the sacrificial coating is etched faster than the group III nitride deposits.
 2. The method of claim 1, wherein the sacrificial coating comprises aluminum, silicon, or both.
 3. The method of claim 1, wherein etching the group III nitride deposits comprises converting the group III nitride deposits to group III halide solids and removing the group III halide solids.
 4. The method of claim 1, wherein the halogen gas is activated by heating to a temperature above 600° C.
 5. The method of claim 1, wherein the sacrificial coating comprises nitrogen and at least one of silicon and aluminum.
 6. The method of claim 1, wherein providing a sacrificial coating on the gas distributor comprises reacting an organoaluminum compound, an organosilicon compound, or a mixture thereof with a nitrogen containing compound to deposit a layer comprising nitrogen and at least one of silicon and aluminum on the gas distributor.
 7. The method of claim 6, wherein the organoaluminum and organosilicon compounds are provided to the deposition chamber through a first pathway and the nitrogen containing compound is provided to the deposition chamber through a second pathway.
 8. The method of claim 7, wherein one of the first pathway and the second pathway bypasses the gas distributor.
 9. The method of claim 6, wherein the gas distributor comprises a first gas pathway and a second gas pathway, the organosilicon or organoaluminum compounds are flowed through the first gas pathway at a first volumetric flow rate, an inert gas is flowed through the second gas pathway at a second volumetric flow rate, and the first and second volumetric flow rates are substantially equal.
 10. The method of claim 9, wherein the nitrogen containing compound is flowed through a third gas pathway that bypasses the gas distributor.
 11. The method of claim 3, wherein converting the group III nitride deposits to group III halide solids comprises reacting the activated halogen containing gas with the group III nitride deposits and the sacrificial coating at a temperature above about 600° C.
 12. The method of claim 3, wherein removing the group III halide solids comprises heating the group III halide solids to a temperature above about 1,000° C. at a pressure below about 50 Torr.
 13. The method of claim 3, wherein the converting and removing are repeated.
 14. A method of removing group III nitride deposits from a gas distributor in a process chamber, comprising: exposing the gas distributor to a halogen containing gas; reacting the halogen containing gas with the group III nitride deposits to form volatile species; and exposing the gas distributor to an active nitrogen containing gas.
 15. The method of claim 14, wherein the halogen containing gas is a mixture of chlorine gas and a carrier gas.
 16. The method of claim 14, wherein the active nitrogen containing gas comprises ammonia, hydrazine, nitrogen gas, or any mixture thereof heated to at least about 500° C.
 17. The method of claim 16, wherein the active nitrogen containing gas comprises ammonia heated to at least about 1,000° C.
 18. The method of claim 14, further comprising exposing the gas distributor to a plasma formed from an inert gas and exposing the gas distributor to an activated scavenging gas.
 19. A method of operating a deposition chamber having a gas distributor with a surface exposed to the processing environment, the method comprising: forming a sacrificial coating on the surface of the gas distributor; depositing a group III nitride material on a substrate in the deposition chamber and on the coated surface of the gas distributor by providing a group III metal precursor and a nitrogen containing precursor to the deposition chamber; purging the group III metal precursor from the deposition chamber using the nitrogen containing precursor; providing a halogen containing gas to the deposition chamber; activating the halogen containing gas by heating the halogen containing gas to a temperature above about 600° C.; reacting the active halogen containing gas with the sacrificial layer and with the group III nitride deposits on the sacrificial coating at a pressure between about 100 Torr and about 200 Torr to remove the sacrificial coating and convert the group III nitride deposits to group III halide deposits; removing the group III halide deposits by increasing the temperature to at least about 1,000° C. and reducing the pressure to less than about 50 Torr; and heat-soaking the gas distributor at a temperature above about 1,000° C. under an inert atmosphere.
 20. The method of claim 19, wherein reacting the active halogen containing gas with the sacrificial layer and with the group III nitride deposits and removing the group III halide deposits are repeated.
 21. The method of claim 20, wherein depositing a group III nitride material on a substrate is repeated.
 22. The method of claim 21, wherein purging the group III metal precursor from the deposition chamber comprises cycling the chamber pressure. 